The present invention relates generally to the wireless remote control of electronic devices, and, more specifically, to the use of remote controls designed for use with various audio-video equipment to also control other types of devices.
The use of wireless remote controls to communicate with host audio-video equipment, such as televisions, audio amplifiers, tape players, video players, satellite receivers, and similar items, is very popular. The typical remote control emits an infra-red radiation signal that has been encoded in some way to designate the various key functions. That signal is then received and decoded by a piece of audio-video equipment, which, in response, performs the commanded function. Different manufacturers utilize different infra-red signal protocols and encoding patterns to command the same functions. For example, the infra-red signal used to mute the audio output of one brand of television is different from, and incompatible with, the infra-red signal used to mute the audio output of another brand of television. So pushing the “mute” key on the remote of one manufacturer is likely not to mute the sound of the other manufacturer's television.
There are many different infra-red signal protocols that are used by various audio-video equipment manufacturers. In the most common types of infra-red signals used by United States manufacturers, a carrier signal, generally within a range of from 19 kHz. to 120 kHz., is modulated into pulses. This is termed Constant Carrier Modulation (CCM). There are several versions of this signal type. In one version, the command being transmitted is designated by the position of the pulses with respect to each other, which is termed Pulse Position Modulation (PPM). In another version of a CCM signal, relative widths of the pulses carries the command information, termed Pulse Width Modulation (PWM). But even when two manufacturers use the same protocol, such as the popular PPM, they most likely will designate different pulse patterns to be generated when corresponding functional keys on their remote controls are pushed. For example, the encoding pattern used by one manufacturer to mute the sound of its equipment is different than that used by another manufacturer, even though both use the PPM protocol.
And there are even more signal protocols that are used by other manufacturers, each of which provides numerous possibilities of specific signal encoding patterns that correspond to designated key command functions. One other protocol is base band pulsing, where signals are transmitted without a carrier. Either the positions of the pulses or their widths can be used to carry the command information, and, as a result, can look similar to CCM encoded signals. Another protocol is Frequency Shift Keying (FSK), wherein each key on the remote control transmits a different frequency carrier signal. No pulses are utilized. Because of such numerous possibilities for the infra-red signals, universal remote controls are popular consumer items. A universal remote control is capable of generating many different infra-red signals for each of the numerous key functions according to the protocols and encoding patterns used by various manufacturers. This allows a consumer to use a single universal remote to control several pieces of audio-video equipment of different manufactures.